Many machines produced today utilize pneumatic and hydraulic systems to power various systems. For example, terminal tractors are specialty vehicles which are used to move semi trailer equipment from point to point around a yard. One type of terminal tractor utilizes a hydraulically activated “5th wheel”—essentially a horseshoe shaped coupling device into which the coupling pin of a trailer is attached. When a trailer is not coupled to a vehicle, it generally stands on static supports at its front, and on wheels at its back. When a trailer is engaged with and coupled to a vehicle having a 5th wheel, hydraulic cylinders lift the 5th wheel via a boom to raise the front of the trailer off of its front supports. In this way, the vehicle can move the trailer.
In current terminal tractors, hydraulic pressure is generated from a hydraulic pump driven by a combustion engine. Generally, when the 5th wheel of a terminal tractor engages a trailer, the terminal tractor is stationary and the engine is therefore idling. At idle speeds, standard motors generally produce sufficient hydraulic pressure to power the hydraulically assisted steering of the tractor, but may not produce sufficient pressure to extend the 5th wheel boom to lift a heavy trailer. As such, workers will often rev the engine during such 5th wheel lifts, causing the engine to operate at a higher rpm than its idle speed. This causes hydraulic pumps within the vehicle to pump faster, producing substantially more hydraulic pressure which allows the 5th wheel to extend and support a trailer. Some vehicles require the operator to step on both the accelerator and the brake at the same time to accomplish a higher motor rpm level, which can harm the vehicle.
Additionally, in current terminal tractors, pneumatic pressure is generated from an air compressor which is powered by a motor. Pneumatic pressure is often utilized in braking systems of such vehicles. As air pressure it utilized to apply brakes, the air compressor is engaged to supply additional pressure. However, as above with the hydraulic systems, there are times that additional power is needed to supply adequate air pressure in many vehicles.
Thus, there is a need for an improved system and method for driving and controlling pneumatic and hydraulic systems, in which vehicle motors are controlled so as to output sufficient power to drive pneumatic and hydraulic systems as needed.